The present invention relates to television switchers, and more particularly to a multiformat television switcher which combines high definition television (HDTV) signal switching and format conversion with an existing master control switcher to provide HDTV upgrade for existing television switchers.
Currently television switchers are designed for a specific television video format, such as PAL, NTSC, SECAM, HDTV or the like. In order to accommodate multiple formats the video source has to be converted into the format acceptable to the television switcher before being input to the television switcher. One solution for a digital video effects device, as embodied in the Kaleidoscope digital picture manipulator (DPM) manufactured by The Grass Valley Group, Inc. of Grass Valley, Calif., United States of America, is disclosed in U.S. Pat. No. 4,743,958, issued on May 10, 1988 to Richard S. Bannister et al entitled "Multiple Television Standards Input Selector and Convertor." This solution has multiple standard format analog video signals as inputs to a source selector, and an adaptive format converter for converting any standard analog video format to a specified digital format which is compatible with the digital picture manipulator. The DPM is set up according to the format of the analog video signal at each input to the source selector. When a particular source is selected, the appropriate commands are applied to the adaptive format converter to configure it to convert the selected analog video signal to the standard digital format.
The analog video signals input to the multiformat input selector described above all share common line, field and frame rates. The input signals all need to be processed in component digital form, so no unnecessary format conversions are performed. However where the input signals have substantially different line rates, and even different field rates, such as HDTV signals versus standard NTSC or PAL signals, unnecessary conversion between formats degrades image quality. Therefore it is desirable to pass signals without format conversion wherever possible.
What is desired is a multiformat television switcher which combines HDTV signal switching and format conversion with existing master control switchers to provide HDTV upgrade for existing television switchers.